Method of assembling electromagnetic horns



May 11, 1954 J. WHITE ET AL METHOD OF ASSEMBLING ELECTROMAGNETIC HORNS Filed March 11, 1949 4 Sheets-Sheet l INVENTORS J06 WHITE AND y Will/AM E BRUNDAGE THEIR HTTOKIVE v5 May 11, 1954 J. WHITE ET AL 2,677,375

METHOD OF ASSEMBLING ELECTROMAGNETIC HORNS Filed March 11, 1949 4 Sheets-Sheet 2 [2 IN VE N TORS J05 WHITE n/va WJ/l/AM F. Emma/we THE/R fi'rralewevs y 1954 J. WHITE ET AL ,67

METHOD OF ASSEMBLING ELECTROMAGNETIC HORNS Filed March 11, 1949 4 Sheets-Sheet 3 INVENTORS J05 WH/n; AND y W/ll/AM BRUNDAGL 17mm fiTToR/vE vs y 1, 1954 J. WHITE ETAL 2,677,875

METHOD OF ASSEMBLING ELECTROMAGNETIC HORNS Filed March 11, 1949 4 Sheets-Sheet 4 INVENTOHS J05 WHITE mm y W/ll/AM I? BAl/NDHGE Patented May 11, 1954 2,677,875 METHOD OF ASSEMBLIN G ELECTRO- MAGNETIC Joe White and William Ind., assignors to Detroit, Mich.,

F. Brundagc, General Motors Corporation, a corporation of Delaware HORNS Anderson,

Application March 11, 1949, Serial No. 80,854

Claims. (01. 29-15558) This invention relates to a sound signal or horn having a diaphragm vibrated by an electromagnetic motor, and cooperating with a projector. In this type of horn, the production of a proper tone is dependent on vibration of the diaphragm at a frequency in resonance with the natural frequency ofthe air in the projector. The frequency of diaphragms made according to the same specifications will vary due to variations in the diaphragm material. Since the projector frequency is non-adjustable, it is necessary to make an adjustment of diaphragm frequency so that a resonant condition will exist. Furthermore it is necessary to prevent the occurrence of conditions which would cause diaphragm frequency to change during the use 01' the horn.

Accordingly, an object of the invention is to maintain stability of the diaphragm so that its frequency change is minimized. This is accomplished by permanently attaching the diaphragm at its periphery to the horn frame or base so that the diaphragm cannot creep relative to the frame and change in frequency.

Another object of the to be attracted toward the armature so that the spacer is clamped between the armature and magnet poles and, while the coil is thus excited, in permanently attaching the horn motor magnet to the base preferably .by welding its core to the base.

Another object is. to simplify the manner of supporting the horn terminal member and of connecting it with the horn magnet coil.

A'further object is to provide forattachment of magnet coil leads'to terminals in such manner that the leads do' not break when the horn is subjected to vibration.

Further objects and advantages of the present invention will be apparent from the following description, referencebeiing had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown. a In the drawings:

Fig. 1 is aside elevation of the hornl Fig. 1A is a view showing a continuation of the projector broken. off from the projector shown in Fig. 1.

Fig. 2 is a plan 1 with the cover Figs. 3 and 4 are sectional views taken on lines 3-3 and 44 respectively of Fig. 2.

Figs. 5, 6 and 7 are sectional views taken on lines 55, 66

Fig. 8 is a sectional view taken on Fig. 2 with the cover added.

Fig. 9 is a plan view of the horn base.

Fig. 10 is a the direction of the arrow H) in Fig. 9.

Fig. 11 is a plan view of a bracket to be welded to the base as shown in dot and dash lines in Fig. 9.

Fig. 12 is a side view of the bracket shown in Fig. 11 and looking in the direction of arrow I2 in Fig. 11.

Fig. 13 is a detail plan view of one of the terminals shown in Figs. '2 and 8.

view of the horn shown in removed.

Fig. 14 is an end view of the terminal looking in the direction of arrow M in Fig. 13.

Fig. 15 is a detailed view of a terminal clip showing a lead attached thereto.

Fig.16 is a side view of the armature assembly for the electromagnet motor.

Fig. 17 is a plan view of the armatureassembly shown in Fig. 16.- 5 v i Fig. 18 is a plan viewof the core or field frame for the 'electromagnet motor.

Fig. 19 is an end view of the field frame look-- ing in the direction of arrow [9 of Fig. 18.

Fig. 20 is a sectional view taken on line 20-40 of Fig. 18, showing a section of the winding in place.

Fig. 21 is a in Fig. 20.

Fig. 22 is an end view of the coil parts looking in the direction of arrow 22 of Fig. 21.

Fig. 23 is a diagrammatic view of -a welding circuit for welding the core to the frame.

Fig. 24 is a fragmentary view showing the use of a shim to'set the air gap between the armature and core.

Fig. 25 is a sectional view showing a fixture for plan view of the winding shown mined relation when the air gap is to be set prior "to attachment of the armature to other parts.

tending lugs 29. g Abracket or shelf is'attached to the base 25 by projection welding. For

side view of the base looking in this purpose, the base is provided with spherical bosses or projections 32 which are engaged by the ears 3| of the shelf 30 during the welding operation.

To the base 25 there is attached a resistor assembly which comprises a disc resistor 35 (Fig. 8), a terminal clip 35, an insulating washer 31, a metal washer 38, a rivet 39 (received by hole 3% in the base 25) and a nonconducting sleeve 40 surrounding the rivet. After these parts are assembled to the base as shown in Fig. 8, the upper end of the rivet 39 is upset. The underside of resistor 35 is grounded on frame 25. The upper side of resistor 35 is electrically connected with the terminal clip 36 which has. prongs 41 which are formed around the insulation 42 of a wire 43. whose end 43a is engaged by Dijongs 44 also in-, tegral with the clip 36. The wire end'ltim is united with the prongs 44 and the clip 35 by welding.

The central opening in the base 25 receives an electromagn'et assembly 50 (Fig. 85 which comprisesa plurality of Eeshaped laminations 5| (Fig. 19) 'of magnet'iron, and; steel plate 52 and 53 (Fig. it) which are attached to the laminations by rivets 54L The plate 5; is provided with lugs or arms d5 provided with spherical projections 58 and'with a tangfifl. Thei'plate' 5,3 is provided with lugs or arms 55having spherical projections 51 and with a tang Egg. After the parts have been assembled, as shpwn i. Fig. 18, a central hole B l is filled, A' magnet coil 62 (Fig. 21) having'terminal wires 53 and 64, is assembled with the laminations" and. plates as shown in Fig. 20. 'As shown'the ccil 5; is wound preferably ma rectangular form and the wires 63 and E i extend along the longer sides of the coil. The i sfif id Q ar f iclo ei .1 le s and 64a, respectively,- of insulating material. The longersides of the windings of the coil and the sleeves are held in a compact relation by strips of tape 65 and the shorter sides oi the windings are held by strips lifi. The strips 65 are offset with en-se is h nt Q 21 5 3 de of the coil so that when the coil, is assembled with wit 9 65 adjacen e t om 5 la provided by the la ations a larger portion of. they sleeves 63c Blic will be pinched becore, thus anchoring the tween the @011 and the w re i nd. M n defini e ne qn wi h. e p to the core. The tangsjii and; Spare bent over as shown in Fig. 8 in orderto retain the coil, 62 in hlfli. re a n. wi h h ore .0,- The arms 55 56 are bent, when necessary, in order tg Qea e h m c tai di tance p t an s mmetrically with respect to the axis :u-y (Fig 8f) which is parallehto the laminations and passes through the center of the hole 6|. The. spacing of the arms is required so that when the electromagnet 'is assembled on the frame the spherical prpjections 5,1 and 5.;8 will move freely relative to the lugs 29 01" the frame without any drag. It is pointed out that. the space between the lugs and-projections is slight sc.v that. it will only require a slight pressure to force the arms against the lugs when the former, arewelded or otherwise fixed to the lugs.

The. armature assembly. shown in. Figs. 16 and 17. comprises a rod having reducedthreaded ends H and 12 and a threaded cylindrical portion 13 which receivcsan armature 1 4, a plate lana ns lan e 6 eei r a a n Wh these 3. r ass h n ne -i ha e i; r nd n qi er n i a et e 1 wi h? i t seal he mew i by aphragm willregister with which threadedly engages the portion I3. The spring 51 is provided with three holes 32a which register with the three holes 30a in the shelf 39. These holes receive rivets 80 by which the leaf spring 21 and other parts shown in Fig. 8 are attached to the shelf 30.

After placing the electromagnet assembly upon the base 25'with the arms and 56 resting thereon, the armature assembly is assembled by passing the rod l9 (not yet assembled with parts {HQ to $35 to be described) through the hole 3i in the magnet core, and the spring 11 is placed upon the shelf with the holes 32a thereof registering with the holes 30a of the shelf 33. Then a loose assembly or stack of parts including a circuitbreaher is assembled. This stack of parts includes in addition to the spring 71 (Fig. 8) a metal spacer 8!, an insulating plate 83, a connector plate 84, a terminal 82, an insulating plate 85, a connector plate 88, a leaf spring 8'3, an insulating plate 88 three rivets 8i} and nonconducting tubes 9B. which surround the rivets. The bracket 83, supports a engaged by a contact 92 spring 8] and project in the plate 88. t d I 8d are swedged over at 93, in order to secure the stack of parts to the shelf 30. The heads. of rivets 80. contact. the bracket 8.9. so

attached to the leaf ing through a hole provided rivets 89, shelf as andframe 25 which is grounded by its mounting upon the frame which a ground strap connects. with a terminal,

94. whi h the diaphragm H3! is aligned. with the. frame 25,;

that notches. lDii (Fig. 2) provided theholes. 21 in the flange 2c of, the frame25 and so that flats it? provided by the diaphragm will extend themanner shown. Then the diaphragm is ate ack e v e he Heme flange is p rm n n ly by spot-welding at a plurality of places designated by the crosses H18 in; dotted lines in Fig. 2.

The next step is to connect. the various leadsv in such a way- With the terminal plates 84 andfifii Theseplatcs are similar in shape, one being a right-hand and.

the, other. a left-hand. Plate 85, is shown inFigs,

13.,and1'4, It has three holesf32b, which receive the rivets 80. andrivet insulator tubes atang 853a. and a tang 861). As shown inFig. 2, the terminal plate 84 has tangs 84a and 8% corresponding totangs 85c and85b ofthe terminal plate 86.

Coil lead wire 64 is place d within the fold of the tang 84a which is bent around the insulation of this wire. The bared end of this wire is placed within the fold of the tang 84b. The coil lead wire B3 and the resistor lead wire 43 are placed within the fold of the tang 860. which is bent around the insulation of these Wires and the baredends of these wires are placed within the fold of the tang 8%. Fig. 5 shows the. manner in which the tang. 86a. is bent aroundthe wires 63 and. 43'. Since terminal plate 85v engages leaf springB'l, contact 92is connectedto.coilleadi3 and the lead 43 of the resistor 3.5 ,hichisgrounde ef e. n rmal v lqse n ae an h ri-s rguit. heres t r .5; hen Qnta contact 9 normally.

e lower ends of the rivets that contact {at is connected to ground through bracket, 89,

of the, vehicle.

plate 88., and a lock. nut, 9.5. are

slightly: dished portion 10a ofv the rod 10 $05 is threaded on the end '92 separates from contact 92, resistor 35 becomes effective to reduce arcing at the contacts.

' In a similar core 50 and the armature I4 when, just before welding the core parts 55 and 56 to the frame parts 29, electric current is passed to the coil 62.

The terminal 82, which is in electrical engagement with the connector plate 84 has its free end bent downwardly; and said end is to provide a cup-shaped member H0. The member H0, receives a screw III for attaching thereto a clip I I2 attached to end of a wire H3 and a clamp H4 having a tang H5 received by a hole in the member H0 whereby rotation of the clamp II 4 is prevented and it serves to prevent accidental rotation of the screw I II by frictional engagement with its head.

The prdjector assembly comprises an upper shell I and a lower shell I2I which are secured together by rivets I22 integral with the upper shell. The upper and lower shells provide the spiral sound passage or column I23 (Fig. 8) which starts at the diaphragm chamber I24 and ends with the shell or trumpet end I25 (Fig. 1). The projector assembly together with a gasket l2! are attached to the base flange 26 by six rivets, four of which are shown in Fig. 2 and are designated by numeral I28. The two remaining rivets are designated by numeral I29 and are each provided with a threaded portion I30 (Fig. 3) and they serve to attach the horn to a mounting bracket, not shown. The arrangement of the six rivets can be varied from that shown in Fig. 2 in order to locate rivets I29 in the required position. By reference to Figs. 4 and 3 it will be seen that the rivets I28 and I29 have bulbous upset portions I28a and I29a which hold tighter than conventional rivets, bulbous upsetting of rivets 6 is well known in the art. Rivet I29 has radial teeth I292? which bite into the softer metal of the projector member I20 thereby resisting the turning of rivet I29 when a wrench is applied to tighten a nut thereon used to attach the horn to a mounting bracket.

The final step in the making of the horn is the welding of the arms 55 and 56 of the horn magnet to the lugs 29 of the frame 25. Before Welding, the armature I4 and the pole faces of the electromagnet are located a definite distance apart. A metal shim I4I (Fig. 24) of predetermined thickness, and preferably magnetizable, is placed between the armature I4 and the pole faces of the magnet core and electric current is caused to pass through the coil 62, thereby causing the magnet core to move toward the armature and bear firmly against the shim MI, care being taken to insure that substantially all the movement is confined to the magnet core and that movement of the armature is inconsequen- By having the magnet assembly loosely assembled with the frame and by providing freecentrally of the frame.

The welding circuit is shown diagrammatically in Fig. 23 in which numeral I 35 designates a welding transformer having a primary coil I36 and a secondary coil I 31 whose leads are connected with welding electrodes pair of lugs 29 while the electrodes I38 and I39 are forced against the arms 56 and 55. While the arms 55 and 55 against the lugs 29. In Fig. 2 these arms are designated by their numerals without the affix, and the numerals 55' and 55' and 29' designate status of these parts after welding.

energy produced by the electromagnet and con sequently the volume of the sound of the horn. For this purpose the nut 94 is adjusted so that ;.which are bentinto notches v-.vi ded, by theprojeotor upper shell L20. The-shell iznormally there is a predetermined clearance sthe, diaphragm .upwardly-beyondits elastic limit nbyaa pull appliedlaxially of the .rod 10. TSince raising the diaphragmfrequency is .notprovided ..ior,;the frequenciesof thediaphragms which. are

used should be resonant frequency or slightly ihigher. Since the @diaphragm is welded toqthe ,frame,;it will, not-creep relative to the frame and itsjfrequencywill not changeappreciably inuse.

Qbviously when the diaphragm is deflectedfor theapurpose .of reducing its frequenQY, its peariphery does not creep relative, to the .frame and, .when thedeflectingforce exerted upon theqrod .Jliisremoved, thereiisno change in relationship between. the peripheral portion of the diaphragm andithe ,frame.

.'I,'he.horn is. now complete except forthe addi- ..tion .of .the back shell [55] which has tangslil I52 (FigVIS) pro- .isprovidedwithan opening-lined with a rubber- ,like grommet I53 through which projects the cuppedpart I I ofthe terminal 82.

,The method oisettingthe air gap between the armature I4 andthepolesil ofcore 50 requires ,maintaining ,a. predetermined relation between the armatureand thebase .25. lntheassembly procedure statedheretoiore, the .arniatureis assemhledwith thespring H which is assembled with ,thebaseshelf 7-30; .and the armature isassembled .withthe diaphragm which is welded to .thebase. This fixes the relation oithe armature 110 the base prior .to setting the air gap. It is rpos'sibleto. fixthe relation of thearmature and the base prior to setting the air gap-Without attachingthe armature to the diaphragm. This relation can be established .by a fixture .plate ,2!!!) tl fig..25) having anannular boss-20! which ,locates the base 25 centrally with respect to ealhioleifll ,in .the plate. .An armaturesubassemblvcan be made including the armature [4 land therod 10. ,After placing the magnet-core .andcoiliassembly upon the base, 25 with the core llocated between lugs 28,and the lugs.55 and ,58 of the core straddling the lugs 29 of the base, the-rod is passed through the holefil ,in the .coreand the. reduced end .1 0a. of the rod is passed into .a hole. 292 in the. plate 200, the shoulder 191) ,Qf,ltherodjlil resting upon a bosslilfi whichsup- ,portsthe armaturele ina location relative-to .thebase 25 which isthesame asit hasin the previously described procedure just vpriorto setting the airgap. The spacer .Mi (Fig. .24) is placedbetween the armature. M and thecore 50 .and themagnetcoilfiZ is excited so that ,the armature, spacerand core are held in contact .by magnetic attraction. The weight oitherod and the armature, air gap spacerand core and coil .assembly supported thereby retains the ,rod shoulder'ltbupon the boss 293. .Thereiiore the ,core 50 is .maintainedin correct relation to the base 25 for the Welding operation.

While the embodiment of the present invention as herein disclosed, constitutes .a preierred form, it isto be understood thatother forms imight :be adopted.

.W hat is claimed ,is ,as follows:

l. The method .of making an electromagnetic sound signal comprising the steps which include.

. ture, and an el p manen ly u in h pe ipheryofiaifiexibl diaphragm to 2. base, -whieh,is,provided with ltwo pairs-of spaced lugaextending froma side thereof remote fromthe diaphragm;dooselyassem- -.a;pair. of arms'of .the core will straddleg-apair of lugs on .the base, said i core supporting a boil;

fixedly connectingan armature to the :central' portion of .the diaphragm by a rod extending through zthe core; placing .an air gap spacerbetrveen the coreand-armature; -excitingthe coil to clamp the spacer between the=armature-and core and therebyteeifect relativepositioning of the base lugs and the'core arms; .and, while-the ,coil is excited, placing a conducting iwedge between-each pair of base lugs. and permanently connecting the core to the base by forcing-weldingelectrodes against .the core arms-and-the latter against .thebase lugs which passes welding current between the electrodes.

In the method. of manufacturing .a horn whi h includes an assembly of a base, aniarma- '-l omagnet having a 'coil and ,a core, the of: .,di.sposing a-coil and coreassembly loosely upon oneside of .abasaproviding .ro l having a locating shoulder: adjacentv its free end, placing an armature on .the shoulder, securing the armature to -the rod,-passing the rod through an aperture inthecore, attaching the rod to flexible diaphragm, permanentlysecuring the .peripheryof the diaphragm to the other side of the base, ,positioning an-air .gap spacer between thecore and the.armature,.-exciting the coil ,toeffect relative movement .between thee-ore .andthe armature to clamp the sp aeer therebetween, to, predeterminately position the core relative .,to.'the armatureand to effect positioning of .the core relative to ,thelbase, and

bore, thesteps of; loosely disposing upon'abase having mountingiugs thereonfor mountin loia core thereto acoil,andcore assembly in which the core has mounting armsior cooperative engagement with thebase lugs, providing arod having a locating shoulder. adjacent its free end, placing an armature on the shoulder,,securingthe armature tothe rod,.passin g the rod throughanaperture in the core, attaching ,therod to flexible diaphragm, permanently, securing theperiphery of the diaphragm to the othersideoi the base, positioning an air gap, spacedbetwecn the eoreand the armature,v exciting the .coil to efiect relative movement betweenthe, core and the armature to clamp the :spacer .thereoetween to predeterminately position the corerelativeto the armature and ,to effect positioning of the core arms relative to the base lugs,-and while the coil is ex- 1 cited maintaining the established relationship .be-

tween thecore and. the armature and-between the core arms. and base lugs by permanently. securing the core arms .to thebase lugs toretainthees- .tablishe :1. relationships.

4. Inthemethod oimakingan electromagnetic sound signal, thesteps-which include, permanently securing .the ,periphery of a .flexible 1di- ,aphragm to onesideof. a, base,-loosely assembling on the base an electromagnet including .a ..core

and a coil disposed in fixed relative position, predeterminately positioning an armature relative to said base by fixedly attaching the armature to the diaphragm, disposing an air gap spacer between the core and the armature, exciting the coil to effect relative movement between the core and the armature to clamp the spacer therebetween to predeterminately position the core relative to the armature and relative to the base, and while the coil is excited maintaining the establishsed predetermined relationships by permanently securing the core to the base.

5. In the method of making an electromagnetic sound signal, the steps which include, permanently securing the periphery of a flexible diaphragm to one side of a base having mounting lugs for an electromagnet extending from the side ately position the cor and to efiect positio tive to the base lugs, maintaining the thus permanently securin lugs.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Roberts Mar. 26, 1929 Reed Mar. 7, 1933 Quam Nov. 5, 1935 Billig Sept. 14, 1937 Emmert May 3, 1938 White Jan. 16, 1940 Baer Feb. 13, 1940 Henninger Aug. 19, 1941 Stem May 26, 1942 Alons Dec. 22, 1942 Cobb Apr. 11, 1944 FOREIGN PATENTS Country Date Great Britain Sept. 28, 1934 Great Britain May 31, 1940 e relative to the armature ning of the core arms relaand while the coil is excited established relationships by g the core arms to the base 

